As atherosclerotic intimal thickening occurs, concomitant outward expansion of the arterial media also develops, with an increase in overall size, a process which may be characterized as arterial "remodeling." These morphological alterations may have profound implications for the obstructive effect of luminal lesions and for the behavior of atherosclerotic arteries with regard to vasoreactivity. The purpose of this project is to define mechanisms that govern the remodeling process and to determine its prevalence and importance in human and experimental arterial atherosclerosis. We plan to do this using newly developed high frequency ultrasonic imaging techniques and by histological methods, in experimental animals and in patients with coronary and peripheral atherosclerosis. Experimental animals will be fed an atherogenic diet; atherosclerotic arterial remodeling will be studied. In patients undergoing cardiac surgery, the influence of arterial lumen shape and circumferential involvement on vasoreactivity will be assessed. In patients with peripheral vascular disease, ultrasonic imaging will be used to detect atherosclerotic vascular remodeling in peripheral arteries. The effect of arterial pressure and metabolic abnormalities such as diabetes on remodeling will be studied. Improved understanding of arterial remodeling will contribute to our overall understanding of vascular atherosclerosis.